1. Field of the Invention
The present invention relates to a polishing pad for a semiconductor wafer and polishing process using thereof. More particularly, the present invention relates to a polishing pad for a semiconductor wafer which can perform a stable polishing while preventing a polishing layer from floating up from a supporting layer and a surface of a polishing pad from bending during polishing using a polishing pad having a multi-layered structure of a polishing layer and a supporting layer, and polishing process using thereof.
2. Description of the Prior Art
Previously, a polishing pad for a semiconductor wafer having a multi-layered structure provided with a polishing layer, a supporting layer and the like has been known in polishing of a semiconductor wafer (JP-A H5-505769, JP-A H6-21028 and the like).
A polishing pad having a multi-layered structure is usually used as shown in FIG. 1. That is, a polishing pad 1 is applied to a surface plate 2 which rotates along an axis, while a semiconductor wafer 4 is attached to one end of a pressurizing head 3. The pressurizing head 3 can make the semiconductor wafer 4 slide on the surface of a polishing pad 1 by rotating and moving itself while pushing the semiconductor wafer 4 against the surface of the polishing pad 1.
At this time, a polishing pad situated under a pressurizing head is pushed to be compressed, and after a pressurizing head is moved, a polishing pad situated at that position is elastically recovered and a compression is released. In such a case, when a porous elastic body is used as the supporting layer, a slurry supplied from a slurry supplying part 5 and the like, or an aqueous medium in the slurry invades in a supporting layer 12 from a side and the like of the polishing pad 1 in some cases by repetition of compression and release. And, the air originally presented in the interior of the porous elastic body is gradually collected into a center part of an interface between the supporting layer 12 and the polishing layer 11, the supporting layer 12 and the polishing layer 11 are peeled, and the surface of the polishing pad 1 is bent in some cases. This phenomenon is not preferable in polishing a semiconductor wafer for the purpose of obtaining high flatness.